The present invention relates to an apparatus for the formation of cigarettes into groups.
The invention is applicable in particular to cigarette packaging machines, in which cigarettes to be wrapped are gathered into groups consisting of a given number of sandwiched layers formed from single cigarettes arranged side by side. Such groups will frequently each consist twenty cigarettes, arranged in three sandwiched layers, namely, two layers of seven cigarettes, and one layer of six.
In certain types of cigarette packaging machines, the three layers of each group are assembled singly at respective forming stations, before being sandwiched together.
In such packaging machines, each layer is formed by dispensing cigarettes to a forming station from a set of substantially vertical channels arranged side by side and provided in number equal to the number of cigarettes in the relative layer. The forming station consists essentially in a chamber, located beneath the dispensing ends of the channels, the bottom of which is embodied as a shelf capable of arresting the progress of the cigarettes that drop one by one from the channels. The single channels are established and separated one from the next by thin, substantially vertical walls, the bottom ends of which are distanced from the shelf so as to allow a clearance marginally greater than the diameter of the single cigarettes.
Given the thickness of the walls and the clearance allowed to the advancing cigarettes internally of the channels, the cigarettes making up the layers do not lie close together on the shelf. In order to supply the wrapping line with properly compacted groups of cigarettes, provision is made at either side of the forming station for pushing means that reciprocate horizontally and in opposition through a direction normal to the axes of the cigarettes; such means serve to compact each newly forming layer from either side closing the gaps between the individual cigarettes.
Nonetheless, it has been found that the action of such pushing means is not always sufficient to prevent the occurrence of drawbacks, in particular when the number of cigarettes in the layer is great, and the aggregate width of the gaps between single cigarettes making up the layer equals o exceeds the diameter of one cigarette.
It sometimes happens in such a situation that, before the pushing means have compacted the layer of cigarettes, the cigarettes themselves tend to drift on the shelf under the weight of the cigarettes in the channels above, to the point of leaving a space between two adjacent cigarettes wide enough to allow the descent, and at least part-insertion, of another cigarette; this can result both in the formation of a layer with one cigarette more than the prescribed number, and in damage to the part-inserted cigarette caused by the transfer indexer that pushes the layer toward a station at which the groups are formed.
The drawback described occurs especially often when the diameter of the cigarettes for packaging happens to be markedly small, as it is particularly easy in such an instance for an additional cigarette to occupy a gap, even a narrow gap, left between two adjacent cigarettes of the forming layer.
Accordingly, the object of the invention is that of setting forth an apparatus for the formation of cigarettes into groups, which will remain free of the drawbacks typical of conventional apparatus as mentioned above.